I wonder the definition of "survival situation" really is. I suppose it can vary.

But I wonder how valid the "availability of ammo" concern really is. I mean, if you're lost out in the wilderness, the only ammo you have is what you brought along. It doesn't matter if it's 22lr or .25-20 Winchester. Even the most common ammo in the world isn't going to be laying around under bushes.

...And if you can somehow get to a store that sells ammo...uh...you've probably reached some form of civilization and maybe don't need to worry about needing ammo to stave off starvation anymore.

Now I can understand if you are someone who purposely lives in or visits the boonies, the nearest shops might have limited ammo selection, so choosing a common caliber makes sense, but again, is that really a "survival situation?"